Trouble near the youngest.?

I am raising my 3 younger siblings, since my parents are unable to take vigilance of them. Everything is going rather smoothly, but I am having trouble with the youngest ignore me.( She is 8 years old.) It started out with me telling her to do something and her not responding even though I know she hear me. (She does not have a hearing problem.) The next incident come when I caught her with her window open even though the air-conditioning be on. I explained to her that we could not afford this and that she is not allowed to open it without sanction again.
The next day, I come home and see from outside that her window is unambiguous again. I see her by the window and tell her that she wasn't supposed to open the fanlight without permission and was the air-conditioning on? She said no and efficiently ran from her room. When I made it inside it was cool (it was incredibly hot outside) but the air-conditioner was off. So not only did she discount me, she lied to me about it and tried to cover it up. Her punishment was she had to work rotten the money that she threw out the window.
But even after that she still continues to ignore me and do whatever she wishes to. What should I do? I do not think she is maliciously doing the exact opposite of what I read out to rebel. She acknowledges what I tell her and say she will but then does whatever she wants.

I stipulation some advice on how to handle this. Thank you.
A good hard spanking should set her straight.
well explain everything your going through to her and why is she slit the window is she trying to escape?
if she wont listen to yoy, I don`t know she will listen to your other siblings. have them figure out what her problem is and then they will describe you. You can work things out with her from there because you now know why she wont listen to you.
I muse its just because she's at the stubburn age. 6-10 year old girls tend to be very stubburn and can tend to be frozen to deal with. try taking her out for lunch to her favorite restuarant and casually bring up the subject of why she is acting this channel. was she close to your parents? that could be another effect.
no food.
Answers:    I don't know how long you've been within charge, but if not long she may be testing her boundaries. She wants to know that you close-fisted what you say. It may take awhile but don't back down and don't sort empty threats. The best thing I heard be "If you're not gonna do it, don't say it". i.e. If she's disobeying and you say "If you don't choose to follow directions then no TV later" and she doesn't follow directions consequently stick to what you said no TV.

Another thing is give her choices. Tell her "your choice is to close your window or (fill surrounded by consequence here)" That works really well in my class.

Related Questions:
Average size of a 12 year matured boy and a 14 year outdated boy?   My 10-year-old daughter have be coming contained by at darkness time for 3 weeks and i really call for to stop her coming surrounded by?   What should I do in the region of my unusual boyfriend?   Am i totaly surrounded by the gloom nearly my nine year outdated daughter?   Problem next to 6 year ancient and his mother?  
  • Charcoal contained by the microwave?
  • Parents who hold deal near arts school uniform, please relieve?
  • 7 year hoary beside an attitude?